General Information NMR spectra were recorded in CDCl 3 (internal Me 4 Si) with a Varian AM-600 (600 MHz 1 H, 150MHz 13 C) spectrometer at room temperature. Chemical shifts () are reported in ppm relative to Me 4 Si (0.00)for 1 H and residual chloroform (77.00) for 13 C. All significant resonances (carbon skeleton) were assigned by COSY (1 H-1 H), HSQC (1 H-13 C), and HMBC (1 H-13 C) correlations. Reagents were purchased from Sigma-Aldrich, Alfa Aesar or ABCR, and used without further purification. Commercial: THF, CH 2 Cl 2 and MeOH were dried over freshly activated (for at least 24h at 250 C) 3A molecular sieves for at least three days. Hexanes (65-80 C fraction from petroleum) and EtOAc were purified by distillation. Other solvents (pyridine, DMF, glacial AcOH and ACN) were used without further purification. Thin-layer chromatography was carried out on silica gel 60 F254 (Merck). Column chromatography was performed on silica gel 60 (70-230 mesh, Merck). Flash chromatography was performed on Buchi glass columns packed with silica gel 60 (230-400 mesh, Merck), using Knauer Smartline system with a Buchi fraction collector. The organic solutions were dried over MgSO 4 .Specific rotation was measured with a Jasco DIP-360 digital polarimeter for solution in CH 2 Cl 2 (c ~1) at room temperature. 5' To a solution of 12 (2.06 g;2.00mmol) in pyridine (20 mL) triphenylphosphine (1.15 g; 4.40 mmol; 2.2 equiv.) and 4-nitrobenzoic acid (0.50 g; 3.00 mmol; 1.5 equiv.) were added followed by a solution of diethyl azadicarboxylate (1.55 mL; 10 mmol; 5 equiv.) in toluene (3.5 mL). The mixture was stirred at rt. for 1.5 h. Pyridine was removed under reduced pressure, the oily residue was dissolved in xylene (20mL), and concentrated to ca. 1/3 volume. Then it was diluted with toluene (10 mL) and cooled to 4 ºC. Precipitated solid was filtered off and washed with cold (T-20ºC) mixture of toluene/hexane 1:1 (20 mL). The solution was concentrated and the residue was purified by column chromatography (hexanes/ethyl acetate 100:1 6:1) to afford alcohol 13 as a pale yellow thick oil (1.91 g; 1.62 mmol; 81%).